1. FIELD OF THE INVENTION
The present invention relates generally to air cooling of a dynamoelectric machine. In particular, this invention is concerned with a dual-face cooling fan mounted inside the housing of an alternating current generator for a vehicle.
2. DESCRIPTION OF THE RELATED ART
It is well-known to cool alternating current generators and other dynamoelectric machines with airflow created by rotating fans. Various combinations of external and internal fans have been incorporated in generators. Generally, air is forced or drawn into a housing in an axial direction along a rotating shaft. The air is expelled radially through vents in the outer surface of a cylindrical housing.
In order to increase airflow and its cooling effect, many generators employ two fans. For example, an external fan can be combined with an internal fan in a generator to increase airflow through the housing. Representative examples of generators having both an external fan and an internal fan include the following U S. Pat. Nos.: 3,422,339; 4,162,419 and 4,604,538. In other machines, a pair of internal fans mounted in series produce cooling airflows which may mix inside a housing before being expelled. Representative examples of generators employing two internal fans include the following U.S. Pat. Nos.: 3,184,625; 3,198,972; 4,418,295; 4,419,597; 4,757,221 and 4,794,285.
The art continues to seek improvement. It is desirable that airflow through a housing be increased to cool the internal components of a dynamoelectric machine. Furthermore, it is desirable that a plurality of separate airflow currents through a housing be provided to increase the cooling efficiency of a fan.